Time division pulse multiplex system



Aug. l5, 1950 w. E. SUTTER ETAL v TIME DIVISION PULSE MULTIPLEX SYSTEM 6 Shee`ts-Sheet 1 Filed Aug. 8, 1949 Inventors: Wa\teT-`- E. Sutter; Thomas G. Cust,

Their Attorn ey.

Aug. l5, 1950 w, E. sin-TER ErAL TIME n'IvIsIoN PULSE MULTIPLEX SYSTEM e ".slelcs-sneetl 2 Filed Aug. 8'1'949 btmwfdf I .Ll

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.SLE :28.3% @zii AU- 15 l950 w. E. suTTER TAL 2,519,083

TIME DIvIsioN v PULSE MurvL'rIvPLEx SYSTEM Aug. 15, 1950 `w.|:.su1`-TER Erm.,

v TIMED'IVISIONIPULSE MULTIPLEX SYSTEM Filed Aug. Ya', 114649 6 Sheets-Sheet 4 lupyglgjllg cLIPPER 5| mFFERENTm-ron 93 cLlPPER AND AMPLIFIER '95 'TIMING SAWTOOTH I I I I I I I CATHODE COUPLED GENERATOR AMPLIFIER 97 98 SYNC. PULSE AMPLIFIERfsEPERAToR 94 Inventors: "Walter E. Sutter; Thomas G. Cust'm,

Thehr` Attovh ey.

W. E. SUTTER El AL TIME DIVISION' PULSE MULTIPLEX SYSTEM Aug. 15, 1950 e sheets-shea e Filed Aug. 8, 1949 Figi?.

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TIME

Their Attovrn ey.

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oscillator II, which may be crystal controlled. The output sine wave I2 is supplied to a timing pulse generator I3 which operates in well-known manner to convert the sine wave into a train of sharp unidirectional timing pulses I4, also recurring at a 30D-kc. rate. These pulses are amplified and inverted in amplifier IE5V and the resultant negative timing pulses I6 are supplied to an output conductor I1, for purposes shortly to be described.

The timing pulses I4 are Valso supplied over conductor I8 to synchronize a frequency divider I9 at a frequency which is asubmultiple of the 30D-kc. frenuency of the timing pulses. In the illustrated form of the invention, which provides for 24 senarate signal channels, theoutput of frecuency divider I9 is a rectangular wave 20 having a l0-kc. repetition rate. These pulses are in turn utilized to control the operation of a synchronizing pulse generator and amplifier whose rectangular output pulses are of the form ,represented by wave 22 adjacent the output conductor 23.

The svnchronizing pulses 22 are also supplied over a conductor 24 to control a lO-kc. sawtooth .wave generator 25. After suitable amplification in amnlier 26, the Vresultant l0-kc. sawtooth .waves 21 are supplied to an output conductor 28.

It will thus be seen that the wave form generator I Il provides three output Ywaves I 6. 22 .and 21. As is best shown in the curves of Fig. 6, all of these waves are accurately synchronized vwith the common 30D-kc. sine wave I2. Two of these waves. the 30G-kc. timing .pulse wave I6 and the lO-kc. timing sawtooth wave 21, are

supplied to all of the channel modulators in parallel, where they are utilized to produce the 42,4 accurately positioned trains of channel pulses .which are interleaved in time division relation in the transmitted signal. each of the channel modulators may be identical, .only three modulators 40, 46a and Miw are represented in Fig. l, corresponding to the modulators for channel No. l, channel No. -2 and channel '.No. 24. respectively.

Each of the channel modulators has thefunction of producing a train of narrow rectangular pulses which are modulated in accordance with the signal intelligence to be transmitted on one .of the channels. In the illustrated form of the invention the modulation is conveyed by means of pulse width. or pulse length, modulation. All v,.ofvthe 24 trains of channel pulses recur at the same IO-kc. repetition rate. but they arel successively displaced in time position, or time phase,

with respect to the common synchronizing pulses. 4rIt will be noted that each ofthe channel modu- -lators 40, lilla-451D is provided with a different .value of adjustable bias potential from a cor- ,respondingpotentiometer section 4|, 4Ia-4Iw.

Allthese sections are energized from a common bias source, represented conventionally by a Thus, a different bias potentialis supplied to each of the channel modulators.

This bias potential, in conjunction with the tim- ,ing pulses I6 and the sawtooth wave 21, provides very precise timing of each channel pulse train in a manner now to. be described.

, In the channel modulator 40, for example, the control voltagesand waves are applied to a channel selector 43, .the timing sawtooth wave. 21 being supplied over conductor 44, the bias voltage being supplied over conductor 45, and the Since the circuits of timing pulses IB being supplied over conductor 46. Channel selector 43 provides a train 0f selector pulses whose time position is conjointly controlled by these three input signals so as to occur at a definite time position with respect to the synchronizing pulses. These selector pulses are supplied to trigger a pulse generator 41 which generates the resultant output channel pulses 48. The channel pulses from each of the 24 modulators are supplied over a common conductor 49 to a final power amplier 50 where they are combined with the synchronizing pulses supplied over conductor 23 to form the composite output wave 81.

In order to modulate each train of channel pulses 48 with desired intelligence, an input signal is supplied over conductor 66 through a suitable ampliier and limiter 6I to a pulse modulator 62. The output of the modulator 62 is utilized to control the length of the pulses generated by pulse generator 41 in the manner which will be better understoodr by reference tothe detailed circuit diagram of the channel modulator shown in Fig. 2 which will now be described.

The channel selector 43 in Fig. 2 is more particularly described and claimed in our copendlng application Serial No. 109,221 filed August 8, 1949, and assigned to the same assignee as the present invention. Briey, it comprises a triode amplifier 63 having the saw-tooth wave 21 applied to its control grid over conductor 44, the bias potential from potentiometer 4| applied to the lower end of a cathode resistor 64 over conductor 45, and the timing pulses i6 applied to its cathode over conductor 46. The amplifier is normally biased beyond cuto by a positive bias voltage applied to its cathode through resistor 64. This bias voltage is gradually overcome by the rising positive portion of the timing sawtooth wave applied to its grid, in conjunction with the negative timing pulses applied to its cathode. The sawtooth wave provides an approximate point of time at which the tube will start to conduct, but this point is very accurately determinedbyI the occurrence ofthe iirst timing pulse which, when added tc the sawtooth wave. raises the grid voltage momentarily above cutoff. As is best shown by the waveforms in Fig. 6, the grid voltage of the amplifier 63 rises linearly along curve 65, from instant of time to, after each synchronizing pulse 22 until at instant of time t1 the combined effect of the timing sawtooth wave and one of the timing pulses initiates conduction. The grid voltage 65 is thereafter limited by the flow of grid current until instant of time t3 at which the sawtooth wave returns to a value below cutoff and the cycle repeats itself.

The sudden conduction of amplifier B3, which is preferably of the sharp cutoff type, produces a sudden drop in voltage at its anode 68, as illustrated by wave 69 in Fig. 6. The rectangular pulse wave 69 is amplified in a triode 15J and differentiated` by means of a short-time-constant network comprising capacitor 1I and resistor 12 in itspanvode circuit, in order torprorducek a triggering voltage of the form represented by curve 13 in Fig. 6. The positive peaks |02 are effective to trigger pulse generator 41, but the negativepeaks ID3 have no effect due tothe negative bias developed across a cathode resistor |04 in pulse generator 41.

The pulse generator 41 is conventionally represented in Fig. 2 as a single-pulse generator of the cathode-coupled type including a double triode 13 whose output is supplied through a comprising resistor |33 and the inherent grid-tocathode capacity |34 of the triode |32. The resultant distorted wave is similar to that represented graphically by curve |35 in Fig. '1. It will be noted that the distorted pulse |36 produced by each synchronizing pulse 22 is of substantially greater amplitude than the remaining distorted pulses due to channelpulses because of itsrsubstantially greater length, or time duration.

The wave |35 is clipped in the stage |32 to leave only the positive peaks above clipping level |29, and these are then differentiated by means of a short-time-constant coupling network comprising a capacitor |31 and resistor |33. The resultant wave appearing at the anode of the next ampliiier stage |39 is therefore generally as represented by the wave |40 in Fig. 7. It will be seen that this wave includes a sharp vnegative pulse 4l synchronized with the trailing edge of each transmitted synchronizing pulse 22.

The Vpulses |4| are utilized to form receiver synchronizing pulses for the timing sawtooth generator 91 by utilizing them to trigger a cathode-coupled multivibrator |50. The multivibrator output is a train of positive pulses. as shown by curve |53, each of which has its leading edge synchronized with'respect to the trailing edge of a corresponding transmitted pulse. The length of this pulse may be adjusted, by means of a potentiometer l so that the sawtooth wave generator may be fully discharged between trains of pulses.

The timing sawtooth generator 91 is represented in Fig. 4 as being of known form in which a sweep capacitor |54 is charged through a constant-current charging network including a pentode amplifier |55. The charging of capacitor |54 is periodically interrupted and it is discharged by means of the synchronizing pulse supplied to a discharge tube |56 in parallel to the sweep capacitor |54. The resultant output sawtooth pulse is then supplied over conductor |51 to a cathode-coupled amplifier S8.

The amplifier 98 is similar in some respects to a. conventional cathode follower since it includes amplifier |00 and output cathode load resistance |6I. However, it also includes a discharge tube |62 Yin shunt to resistor |6| which is rendered conductive in synchronism with the discharge tube |55. The primary purpose of the discharge tube |62 is to avoid distortion ofthe sawtooth wave which is supplied to the highly capacitive load comprising the 24'channel demodulators and connecting cables. It prevents distortion by discharging the load capacity at the end of each sweep of the sawtooth sweep voltage.

Referring now again to the block diagram of Fig.` 3, it will be noted that each of the 24 channel demodulators, of which only three demodulators |10, |a and |1010 are shown, has the same circuit arrangement. Thus, each of them comprises a channel selector lll, a gate generator |12, a gated demodulator |13 and a low pass lter and audio amplier |14. The amplified and clipped video signal |00 is supplied to all the gated demodulators in parallel over conductor 92.

Each of the channel selectors is also supplied, iny

a manner similar to the channel selectors of the transmitter, with the 30D-kc. timing pulses, the lll-kc. timing sawtooth wave, and an adjustable bias voltage. As in the case of the transmitter, this bias voltage is Ysupplied from one of the respective sections |15, |a|15w of the potentiometer which is energized from a bias source conventionallyr represented as acommon ybattery 1.16.5.V H:

The circuits of a channel demodulator are shown in greater detail in Fig. 5. The construction and operation of the channel selector |1| may be identical to that of the channel selector 43 in the transmitter. The accurately timed trigger pulse at the output of the channel selector, corresponding to the desired channel pulse to be detected, is supplied to the right-hand section of a dual triode |80 in the'gate generator |12. This section operates as a driver amplifier for the lefthand section, which is connected in the circuit of a conventional blocking oscillator |8|. The output of the blocking oscillator |6| is a relatively narrow rectangular pulse |82 of relatively high voltage (about 100 volts, for example).

The gated demodulator |13 comprises a pentode amplier |83'having vthe gate pulses |82 supplied to its screen grid and the composite video signals applied to its control grid. A suitable value of positive cathode bias voltage is impressed so that the tube |83 is normally noncondu'cting and the length-modulated channel Y pulses are supplied to an amplifier stage |84 only when' they are coincident with the gate pulses |82.

Thus, a selected train of channel pulses, recurring at the basic 10kc. rate, is supplied from the output of the amplier |84. These pulses are generally represented by the curve |35 in Fig. "8 and the approximate limits of their length modulation is indicated generally by the small horizontal arrows.

The pulses |85 are integrated by means of a coupling network comprising resistor |86 and capacitor 81 before being supplied to amplier |84. This network has a relatively long time constant as compared to the duration of the pulses, so that the peak amplitudes and areas of the resultant pulses are dependent upon the degree of width'modulation. Thus, the resultant pulses supplied to amplier |84 may be generally represented by the waves |88 and 89 in Fig. 8 under conditions of. minimum and maximum pulse length, respectively.

The original modulation signal is now recovered in known manner by passing the wave through a low pass filter |90 and amplifying it in a suitable amplifier represented as a two-stage amplier |9l. rlhe iilter |30 is represented as a conventional four-section filter having series inductance sections and shunt capacity sections.

From the foregoing description of our invention,it Vwill be seen that we have provided simple and effective means for positively synchronizing all of the circuits of both the transmitter and receiver terminals of a time division pulse multipleX system with respect to the single master oscillator in the transmitter. `Each of the individual trains of channel pulses is utilized to generate 'one of the gate pulses in the receiver. Thus, a relatively large number of channels can be accommodated without interference and cross-talk. While our invention has been illustrated in its application to a 24-channel, high fidelity pulse multiplex system, it will be understood that it is not limited to this precise number of channels or to theprecise frequencies mentioned. Actual asifsge 1o tiraiifvarious modiicatons mayloefmadefwithoui and means-l fondemodulaeing" each of f said rsei-- deprtng from the invention The appended lectedgroupsmtoreproduce-each of said signals.'

claimsaie .therefore intende@to-eovenany such Q'Aimedivisiorr pulse-multiplex system com inodini-:ationslwith-in-` tl'ieetrue-spiirit and scope of prifs'ng-'afiransxnittirg sia-tion including amast'e the. imention.A 5 esci-llfatigsource meanssynchronized; from sail Whatwwe claimasnewandf desirelto secureby sourcef fon' generala-ifng1 a"trainoftimingf pulses Letters Patent-on the `'lll'ni'ized States-is: spacedf'apalt byafdesiedchannelspacing;means A-time division. pulserrluliaiplex` systemcomeJ also s ynchroniedifronrsaidr soureefengenerating prising aftran-smiltin'gzstationincludingaimaster a-group of'synhionizingfpulses havingea. desired osciliatifonlsomrce;meanssynohronized irom said? 10. gfougspaeing; meansconjointly-f controlled by source-iran" producing .af groupio synchronizing safiolf timingff'and synchronizing pulses -for1 genpul'sesfcat-'iadesired".grouprequeney; .meansl also erating -avpliur off time-displaced groups kof synehronizedirom sai'cl sourcefffonlproclucing n; chan-nei paises; means for# in'dividuallyv modupIu-rality of groups/ofchann'el.- pulses recurring ai: latingtliie"pulse'lengihs lin-Jeaehv -of vsaid groups sadifrequencybutprogressiveiyi'bimeedisplaoed 1.5. of-"ehanneljf'polsesf Wiihwa-desifrcd signal toh be soA as tofpeinterleaved with each' otherandvwitla multiplexed; andfmeans'for-combining -andti'ansi said? synchronizing pulses; .means .fo-Ifnmodnlatingf mittingfalif'- i saith pulse@ gre-ups-v in- Vtime division eaclfi'of saidfgroupsfoichannelpuls'esrwith aide@`V multiplleafeiaiiion; andfalreoeiving station" insiireol signah .ltovbel multiplexecLi 1 anniV mear-rsu` fon Shilling f-lneansf@onr` deriving aJ receiver synchrosomebiningfand!transmitng allfsaid.pulse.groislpsgl 20 raining* wave'- frenn said l synehronizing-A pulses; 'a,.pggewmgrsbatibn. migludngmeansi meansi'on d'eiivingv individual selector pulses. ivingf a timing; wane from` said =synchron from leaeiioisaidfehannell-pulses:eaehvvsynchi'oe pulses-means .fmpf @giving individua-1:1 timingf alizeelfiwilall the leading ed'gefoa corresponding pulses fromeachioisaidchannel pulses.rv means; Peceiv'ed channelsI pul'seg.; means -con'jointlyfconi eo'njoiz'afclrr eontirolizgdf:rmaz said: timingffwave and 25 tnolledvbysa-id synchronizing Wave and -selectoit tfmingmulgesffgp gepamteiySelectingfeach @ffsaidi pulses lfon-seleoting---eaollo said 4,time-ciispl'aee'd gnaupsfiof-fchannel puise's', =ancifimeans .fon des gnoups-'oi' ehannelipulsessandmeans for demoduimodulating eaehiofsamt-:selected: groups. msnen-ii lating each Aonsaid:seleeiierif-groping,E toreproduce produce-Galenofisaidisignals. l eaclfrrolsaidi-sisggrlals.sl f u i 2iA-timefdivision pu-lse muli'fipl'exasystem;comeV 30 Atime1diyision fpul'semnltipleie system-1comev pnisingnatransmttine statinmincmdlingia masten Yprisme-fa transmitting@Staien-ineludnelahigif oscillation sounce-,iAmeansiisynchnonizedfnomlsaid feqllnyi' master oscillation generator, meansisouncef' .for 41pendueing:a group.N ofu synchronizing synelfnonilzedxfromlfsaid-genenator producing:- puses; atarzdesird group@flaque-nay.;. means'also; av-na'inof.; synchnonizingf"fpnlsesrat Sa,- submuitiipla synchnonizedzfmmsisaid sourcezfonproducing.a 35 @i-fsaid ilfe'quenygmeans-synchronizedliromf.said

plurality 'oit groupsifofscnanneh.pulsesniiecmiring genenatorflf'or: pifoduoing.alplnnality oichannell atm said; frequency: "but-f pmgresswelyf timedisspulse.v prainsnfeach.. -having saidsubmultiple freiplacedvrso asiato.. be: interleaved; with 'each other; euerlcy andipwgmssively time-displaced with` veel and: with u said; rsynch'ronizingf' pulses, .xmeana for speen f to :saidil lsynhigrlZ-ng pulse brain, "meanf modulating#thewfpulse.: lengths: sacri-:.015 saint im fon1inoliniduallyf.modulating4 length; op Ath@ .ch-am,` groups ofi lchannf-il,` .puls'es.:{wil-,liV a l desiredizignal; neL pulsesv inieach-:tnainz withizfespectt toione edge; tao bemultiplexed', and ..meansnfon` combining.; and: thereof. vini aevdan 'Si Siglail: to. be. multif-L tizansmittingwall;sant.pulse` groups; and a" :la1 plexedgi .means florz combining said!A trains.' into. eeiwingfstabion :including: meansffier '.derixzfing; a; periodic pulse groups eaclfnhavingfanzinitialgisynn timings wanefinomasaidmsynchnonizing'pulses; ehronizingflpulse; folluwed-floy:onevchannel. pulse means.fon'.deriningyindixgidualtiming pulsesz'fitomi mmceach; Yilbm: and,V ai.y receiningnsiiation; each; 'on said.' chan-nek pulses :sache-synchronize@ Gllid-ngimni 411 deriving?tmingwaveiinom .the leaiingdge; thereon. means.`| coniointiw Said-f syn,c-.lnzoliti-Zing;ipulses, mwne' fm1 deriving eontnolleazhysaid `timing: wanezanoi timinnpnlses iniv'rdualitimnepulsesffrom. said. channel. pulses ton-sepanaielyi selectingleach: ofi-said groups-.coli go, each Sy'rwh'mnzediwitln sainhedeefof. agrespetv;

channel pulses, and means for demodlilaiiJlII-g:.emfl;` @hannah puleswmea'ns; Jceliioinlyi' contnolled/be on saide seleeten?gnoupntmgepmduce each of.. 'said aaidabimingywaweiand@timings Wheaton-separatelysignal-s.;v selen tixieia` each of: .sfaidffclzannel nulse-tifains-- and; ,3,=. a'timediwisiompulse-lninltiplensnstem@,come means ffm@ @modulating-each? oi* saicliseleeued: prisingsa/transmi, ingstiaiiionneludnQa massen M bral. l .'dueef-eachof .s ai'd-l signals. QSllaiOn saurameanasynehnonized fnomisaiq 6.- A. tuned. impulse nnrltiplexsysigenfncome4 Source,vk fer generamg Liainxofytiminaenulses nrisinea-bnansmitiiinetermmaiincluding.. high Snapeapaetibyia;desiized channelispac frequency 'maaien esillainn; eeneratolz. means. also synnrqnizedfnorm sani soumeofxfrgemen l synhroniaed. fmmfsaid generator' for nmducina man gneunnf synehrenizing-.pnlses having-af i siiie.,d.gnoupzspaeina,=ineans conjointla muenchen lena byfsaid'timingaan s-Mnohnonizingipulses@fon gene Saldflequen Seating, al plurality of: time-.displacedigmiipsao generali@ i016 @indue @hanna -pu1ses;.means=.for individually-amenace puise. trains en e? eel. mereacnofssaid gno psa chann' nulsesfwifbli @luenenandifpreerewelntimedisnlaeed-wtni1ee sneeifiof Sai@ eynenrenizing :pulse traire. means fonfind l 11 f meenlatine the -leneiin of; the groups; inirti'mce;x lvsionrmultipleic Rafael?! 1:'l C. h: aireoeiwngf'sbai finelndingz-mean ffenfdeeiwnsdgGherQf 1.11 aeGQdazlnewlth afrecei-veie synemonizinafwavew-fnom saiqesme 72o multiplexed the# length: Qff @een saisi @nonnina-.pulses@meansfond, .me ind' 'einen i menu-late enamel pulse beine; than; said; selector 4pulses.frein.: eaohf-eff s h medeierrnlried1er1gifl.-l,l means for eombinine sain meansaconliointlyconta-oiled. mosaici. synchronize l'rlpains-finioi periodi@ 1:,i1lsev gmupss each having ani ingewayee andsselections'puisesi:forol each initah synchronizing? pulserfollowedfzbyfone chan@ timefdisplacef-groupsgfo channel pulses; (5 neispulsaiirom calchiir-aim4 .ancha receivingiteize minal including meansfor integrating saidireceived pulse groups and deriving a timing Wave from said synchronizing pulses, means for concurrently diierentiating Asaid received pulse groups and deriving individual .timing pulses from said channel pulses each synchronized with said edge of a respective channel pulse, pulse selecting means conjointly controlled by said timing WaveY and timing pulses forseparately selecting each of said channel pulse trains, and means for demodulating each of said selected trains to reproduce each of said signals.

7. A time division pulse multiplex system comprising a transmitting station including a master oscillation source, artiming pulse generator synchronized from said source for generating a train of timing pulses spaced apart by a desired channel spacing, a synchronizing pulse generator also synchronized from said source for generating a train of synchronizing pulses having a desired group spacingfa plurality of channel modulators each conjointly controlled by said timingV and synchronizing pulses for generating a train of channel pulses at said group frequency, means f or independently-adjusting the phasing of each modulator to synchronize it with a different tim-l ing pulse in each group, means for modulating each of said trains of channel pulses with a desired signal to be multiplexed, and means for combining and transmitting said groups of synchronizing and channel pulses; and a receiving station comprising means for deriving a group synchronizing Wave from said synchronizing pulses, means for deriving from said channel pulses a group of selector pulses each individually synchronized with a corresponding channel pulse, a plurality of channel selectors each conjointly controlled by said synchronizing Wave and said selector pulses, means for adjusting the phasing of each said selector to select a diierent channel pulse from each group and a corresponding plurality of demodulators for detecting and translating the signal modulation of each train of Selected channel pulses.

, 8. A time division pulse multiplex system comprising a transmitting station including a master oscillation source, a timing pulsev generator synchronized from said source for generating a train of timing pulses spaced apart by a desired channel spacing, a synchronizing pulse generator also synchronized from said source for generating a train of synchronizing pulses having a desired group spacing, a plurality of channel modulators each conjointly controlled by said timing and synchronizing pulses for generating a train of channel pulses at said group frequency, means for independently adjusting the phasing of each modulator to synchronize it with a different timing pulse in each group, means for modulating the pulse lengths in each of said trains of channel pulses with a desired signal to be multiplexed, and means for combining and transmitting said groups of synchronizing and channel pulses; and a-receiving station comprising means for deriving a group synchronizing wave from said synchronizing pulses, means for deriving from said channel pulses a group of selector pulses each individually synchronized with the leading edge of a corresponding channel pulse, a plurality .of channel selectors each conjointly controlled by said synchronizing-wave and said selector pulses, means yfor adjusting the phasing of each said selector to selecta differentl channel pulse from each group and a corresponding plurality ofv demodulators for detecting andtranslating the sig- 12 nal modulation of each train ofselected channel pulses.

9. A time division pulse multiplex system comprising a transmitter terminal including a master oscillation generator, means for generating periodic groups of pulses, each group comprising an initial synchronizing pulse followed by a train of spaced channel pulses, the pulses in each group being individually synchronized from said generator, means for modulating the length of each channel pulse with respect to itsleading edge in accordance with a signal to be multiplexed; and a receiving terminal including means for deriving from said groups a timing wave having the group frequency, means for differentiating said groups and deriving therefrom a train of timing pulses each individually synchronized with the leading edges. of the received channel pulses, a plurality of 3pulse selecting means each conjointly controlled by said timing Wave and said timing pulses forselecting adifferent modulated channel pulse in each group, and a corresponding plurality of means for demodulating each of said selected pulses; to reproduce each 'of said signals.

10. -A time division pulse multiplex system comprising a transmitter terminal including a master oscillation generator, means forY generating periodic'groups of pulses, each group comprising an initial synchronizing pulse of predetermined length followed` by a train of spaced channel pulses, the pulsesin each group being individually synchronized from said generator, means for modulating the length of each channel pulse with respect to its'leading `edge in accordancewith aj signal to be multiplexed; the maximum length of each said modulated channel pulse being less than said pre'determinedlength; and a receiving terminal including means for `integrating said received pulse groupsand deriving therefrom a timing Wave having the group frequency, means for simultaneously differentiating said received pulse groups and deriving therefrom a train of timing pulses eachindividually.synchronized with the leading edge of a received channel pulse, a plurality of pulse selecting means each conjointly controlled by said timing Wave and said timing pulses for selecting a differentmodulated channel pulse in each group, and a'corresponding plurality of signal detecting means for demodulating each of said selected pulses to reproduce each of said signals.

.11.A time division pulse multiplex system for producing a composite pulse signal consisting of periodically-recurring pulse groups each comprising an initial synchronizing pulse followed by a plurality of time-spaced, Alength-modulated, channel;` pulses, said groups recurring at a frequency higher than the highest modulating fre.- quency, comprising in combination, means for generating a master control Wave having a high frequency which is a multiple of said group frequency and equal to a desired frequency of recurrence of said channel pulses, means for convertingsaid Wave into short channel timing pulses at said high` frequency, frequency dividing means controlled by said Wave for developing said synchronizing pulses atY said group frequency, a plurality of channel modulators equal. tothe number of modulating signals to be multiplexed, each said 'modulator including a pulse generator conjointly controlled by said timing and synchronizing pulses fordeveloping one of said channel pulses, means. for .adjusting the time positionsv of said channelpulses so that eachV occurs in synchronism .w1th-:.a. different timing i4 1j. s .ffii .slecfms prede. "finaal" ha pulsel rom' each group, and mea's forA defiod latiig each ofl said selected channel pulses to re" I Vpofllfe; the mQdulatingsig'naly `/In ya'tifie division pulse multiplexms'ystexn; f'the': typi' wherein a composite pulseWavefc'orjf` sis ,tir1', g;v of' perio'diallyrecurring pulse groups 's transmitted, yeachgroup omprisingwan ,alf sly'riqronizins" pulse' follwed .bv a plurality; ofi s 'ced channel 'pulses which aref separately lengtherradulatedby modulatinasisnals, each oli Saidynchronizing' pulses' having' slibstan4 synchronized with said .V synchronizing puls iie'a'ns for. concurrently diferelntiating saidwa saidzontrolpulss and'sid' imis P111 seleting'one predetermined; channelzjls vfr0 h group,.;a1.1d.meanszfordmodulat e I "f icl selected channel pulssto reproduce eanl 0' i Mij Atinfle d ivisiqn pulse multi s'acpmbit PHSLSW g 1n o0 ion", In

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channelpulegeachtet by. said contrQl warearid 90,. .trQl pulses@ ing one `predeterir1ir1..f.:dc11.anne;pulseiff. smul),y and;.means.fQrdemoldulatinssaqh -selectedfrclfiannel pulses to reproduce the modulatins Signal 14,` A` time division` pulse. multiplex recaycr. fQr receiving, a Composite pulses/ave 0f .the type.` conf sistng of periodically-recurring rv ..pulsej `g groups, eachfgroup comprsngfan initial, relatively long, synchronizing pulseigfo'llowed by a plurality of substantially shorter time-displaced channel piu pulses each of whichis-'spratel modulated by fjl intelligence-bearing Signals, COmDISiIlg in 00mfor selecting a different channel pulse from each bination, means for deriving from said synchro- 70 group, and means for demodulating each of the IlZng pulSeS a SFILW'OOth Control Wave Synresultant trains of selected channel pulses to rechonized therewith, means for deriving from each produce the modulating Wava of said individual channel pulses a control pulse 18. In a time division pulse multiplex system ,synchronized therewith, means conjointly conof the type wherein a composite `pulse Wave controlled by said sawtooth wave and said controlfl sistingrof periodically-recurring pulse groups iS @page 1 5 transmitted, each group comprising ank initial rectangular synchronizing pulse followed by Ya plu ralityof spaced rectangular channel pulses which are separately length-modulated by modulating. signals, each of said synchronizing .pulses hav-'- ing substantially greater length than any channel pulse, a receiver kfor said wave comprising means for integratingsaid wave and deriving control pulses therefrom each synchronized with one Aof said' synchronizing pulses, means synchronized from said control pulses for generating a.' sawtooth wave at thegroup frequency, means for concurrently differentiating .said composite wave and deriving therefrom groups of time-displaced timing pulses each individually synchronized with the leading edge of one of said modulated channel pulses, plurality of channel selectors each conjointly controlled by said sawtooth Wave and said timing pulses for selecting one predetermined channel pulse from each group, and means for demodulating each oi said selected channel pulses to reproduceeach or said signals. 19. A time division multiplex receiver for operation with a composite pulse wave of the type consisting of Vperiodically-recurring pulse groups whose group frequency is higher than the highest modulating frequency to be received, each group consisting of an initial rectangular synchronizing pulse followed by a plurality of progressively-displaced rectangular channel pulses each of which is separately lengtli-modulated with respect to its leading edge by a desired signal, and said synchronizing pulse having a length greater than themaximum length of any channel pulse, comprising in combination, means including an in- Y tegrating network having a time constant longer than each synchronizing pulse for deriving `from said wave a rst train of group timing pulses synchronized. with said received synchronizing pulses, means including a diierentiating network having a time constant shorter than any channel pulse for concurrently deriving from said wave a second train of sharp pulses, said second train including pulses of one polarity synchonized with the leading edges of said received channel pulses, means comprising a plurality of channel selectors each conjointly controlled by said group timing pulses and by said pulses of one polarity for selecting one modulated channel pulse from each group, and a corresponding plurality of means for separately demodulating each resultant train of selected channel pulses to reproduce the desired signal.

20. a time division multiplex receiver for operation with a composite pulse wave of the type consisting of periodically-recurring pulse groups, each group consisting of an initial rectangular synchronizing pulse followed by a plurality of lprogressively displaced rectangular channel pulses leach of which is separately length-modulated with respect to its leading edge by a desired signal, and said synchronizing pulse having a length greater than the maximum length of any channel pulse, comprising in combination, means for supplying said wave through an integrating network having a time constant substantially longer than each synchronizing pulse, means for clipping said composite wave at the output .of` said network and deriving therefrom a Ytrain of group timing pulses synchronized with said synchronizing pulses, means for producing a selector wave'having the vfundamental group frequency and synchronized with said group timing pulses, means `lor concurrently supplying said composite Wave through a differentiating network having a time constant substantially shorter than the minimum length of any channel pulse, means for clipping said composite wave at the output of said differentiating networkand deriving therefrom a train of selectorV pulses each synchronized with the leading edge of a received channel pulse, means comprising a plurality of channel selectors each conjointly controlled by said selector Wave and by said selector pulses for generating train of control pulses, means utilizing each control pulse to select one channel pulse from each group, and means for detecting the desired modulation signal in each train of selected channel pulses.

21. A time division multiplex receiver for operation With a composite pulse wave of the type consisting of periodically-recurring pulse groups Whose group frequency is higher than the highest Vmodulating frequency to be received, each group consisting of an initial rectangular syn-` chronizing pulse followed by a plurality of progressively-displaced rectangular channel pulses each of which is separately length-modulated with respect to its leading edge by a desired signal, and said synchronizing pulse having a length greater than the maximum length of any channel pulse, comprising in combination, means for supplying said Wave through an integrating network having a time constant substantially longer than each synchronizing pulse, means for clipping said composite wave at the output of said network and deriving therefrom a, train of group timing pulses synchronized with said synchronizing pulses, a sawtooth wave generator, means for synchronizing said generator at saidrgroup frequency from said group timing pulses, means for concurrently supplying said composite wave through a diierentiating network having a time constant substantially shorter than the minimum length of any channel pulse, means for'clipping said Wave at the output of said diierentiating network and deriving therefrom a train of channel selector pulseseach synchronized with the leading edge of a received channel pulse, a plurality of channel Vselectors each normally biased beyond cutoff, means for applying both said sawtooth wave and said channel selector pulses to each said selector in a sense tending to overcome said bias, means for independently adjusting the bias on each selector so it becomes conductive on occurrence of a different selector pulse, means utilizing the output of each selector to form a channel gate pulse, and a corresponding plurality of gated channel demodulators to each of which said composite wave and one of said gate pulses is supplied,fsaid demodulators each selecting one channel pulse from each group and detecting its Amodulation signal.

WALTER E. SUTTER.

THOMAS G. CUSTIN.

No references cited. 

